How do you launch the JavaScript debugger in Google Chrome?

Windows and Linux:

Ctrl + Shift + I keys to open Developer Tools

Ctrl + Shift + J to open Developer Tools and bring focus to the Console.

Ctrl + Shift + C to toggle Inspect Element mode.

Mac:

⌥ + ⌘ + I keys to open Developer Tools

⌥ + ⌘ + J to open Developer Tools and bring focus to the Console.

⌥ + ⌘ + C to toggle Inspect Element mode.

Source

Other shortcuts

Try adding this to your source:

debugger;

It works in most, if not all browsers. Just place it somewhere in your code, and it will act like a breakpoint.

Windows: CTRL-SHIFT-J OR F12

Mac: ⌥-⌘-J

Also available through the wrench menu (Tools > JavaScript Console):